When doing a backup of all mailboxes each mailbox begins to back up, but after about 20 megs of mail has been copied, the rest of the mailbox errors out with nothing but the following types of messages.
File "xxxxxxxx\Tasks\00000000076aae4646b50844992ddd6a70ebfc730700d3504ef8dd7fba469bda4d41d69c5df90031e4fa9cb900000ebd54e325cc124c8d158f4deb347261003451e316020000": can't read, error -3405 ( unknown)
File "xxxxxxx\Tasks\00000000076aae4646b50844992ddd6a70ebfc730700d3504ef8dd7fba469bda4d41d69c5df90031e4fa9cb900000ebd54e325cc124c8d158f4deb347261003451e316030000": can't read, error -3405 ( unknown)
The weird thing is, that every time I back up I get another (new) 20MB of mail before it errors out. I've looked at the KB article, I'm using an RBU. I've relicensed exchange. It does this regardless of the storage device, and does it on brand new catalogs. I've updated the MAPI components. I've even wiped out my configuration for Retrospect, uninstalled and then reinstalled the whole thing. The behaviour is identical every time.
I also dismounted and scanned the databases for errors, with no results.
I'm at a complete loss. Any ideas?